Commit fbfa9260 authored by Sudeep Holla's avatar Sudeep Holla Committed by Thomas Gleixner

clockevents: Warn if cpu_all_mask is used as cpumask

Using cpu_all_mask in clockevents cpumask may result in issues while
comparing multiple clockevent devices to choose the preferred one.

On one of the platforms with 2 system (i.e. non per-CPU) timers with
different ratings, having cpu_all_mask for one of the device resulted in a
boot hang due to a endless loop in clockevents_notify_released() as both
were clocksources were selected as preferred.

In order to prevent such issues in the future, warn if any clockevent
driver sets cpu_all_mask as it's cpumask and just override it to use
cpu_possible_mask. All the existing occurrences of cpu_all_mask are already
replaced with cpu_possible_mask.
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lkml.kernel.org/r/1531308264-24220-3-git-send-email-sudeep.holla@arm.com
parent 234b3840
......@@ -463,6 +463,12 @@ void clockevents_register_device(struct clock_event_device *dev)
dev->cpumask = cpumask_of(smp_processor_id());
}
if (dev->cpumask == cpu_all_mask) {
WARN(1, "%s cpumask == cpu_all_mask, using cpu_possible_mask instead\n",
dev->name);
dev->cpumask = cpu_possible_mask;
}
raw_spin_lock_irqsave(&clockevents_lock, flags);
list_add(&dev->list, &clockevent_devices);
......
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